This invention relates to the preparation of 1,3-propanediol, especially to a cobalt-catalyzed process for manufacturing 1,3-propanediol in high yields without the use of a phosphine ligand for the cobalt catalyst.
1,3-Propanediol (PDO) is an intermediate in the production of polyesters for fibers and films. It is known to prepare PDO in a two-step process involving (1) the cobalt-catalyzed hydroformylation (reaction with synthesis gas, H2/CO) of ethylene oxide to intermediate 3-hydroxypropanal (HPA) and (2) subsequent hydrogenation of the HPA to PDO. The initial hydroformylation process can be carried out at temperatures greater than 100xc2x0 C. and at high syngas pressures to achieve practical reaction rates. The resulting product mixture is, however, rather unselective for HPA.
Alternatively, the cobalt catalyst has been used in combination with a phosphine ligand to prepare HPA with greater selectivity and at lower temperature and pressure. However, the use of a phosphine ligand adds to the cost of the catalyst and increases the complexity of catalyst recycle.
There are a number of prior art references which relate to 1,3-propanediol production including the step of hydroformylation of ethylene oxide using a cobalt catalyst in the absence of a phosphine ligand, using other ligands. See, for example, the following U.S. Pat. Nos. 5,981,808, 5,463,145, 5,463,146, 5,545,767, 5,731,478, 5,723,389, 5,786,524, 5,841,003, 5,576,471, 5,563,302, 5,545,765, 5,463,144, 5,770,776 and 5,585,528.
U.S. Pat. No. 4,096,188 describes the preparation of straight chain olefins by catalytic hydroformylation with carbon monoxide and hydrogen in the presence of cobalt catalyst and primary secondary or tertiary amine modifier.
According to the invention, 1,3-propanediol is prepared in a process which comprising contacting ethylene oxide with carbon monoxide and hydrogen in an essentially non-water-miscible solvent in the presence of an effective amount of a non-phosphine-ligated cobalt catalyst and an effective amount of a primary or secondary amine promoter at conditions effective to form 3-hydroxypropanal. It is especially advantageous to use a lipophillic amine and to employ a non-water miscible solvent. Usually the reaction conditions comprise a temperature within the range of about 50xc2x0 to about 100xc2x0 C. and a pressure within the range of about 500 to about 5000 psi. Conveniently, an aqueous liquid can be added to the intermediate product mixture at a temperature less than about 100xc2x0 C. in order to extract a major portion of the 3-hydroxypropanal into the aqueous phase an to provide an organic phase comprising at least a portion of the cobalt catalyst or a cobalt-containing derivative thereof and at least a portion of the lipophilic amine. The phases can be separated and the aqueous phase comprising 3-hydroxypropanal hydrogenated to produce 1,3-propandiol.
The process enables the production of 1,3-propanediol in high yields and selectivity without the use of a phosphine ligated cobalt catalyst in the hydroformylation step. The process also enables the recovery and recycle of essentially all the cobalt catalyst.